The short answer is, no, Ruby on Rails is not a dead language. The truth is that Ruby just got a recent minor update to 2.7 with a 1.7x increase in performance and is expecting a major update added to Ruby 3 in 2020. Ruby on Rails is not dead, its evolving.
Is Ruby still alive in 2021?
its 2021, and ruby 3.0, and ruby on rails 6.1 are alive and thriving.
Is Ruby still worth learning in 2021?
Whats wrong with Ruby?
Rubys standard library is just plain buggier and less functional than Java/Python/Clojure. In some cases, this is missing functionality that you would expect in a stdlib, and in some cases, the ruby version being less functional / configurable than pythons.
Does Google use Ruby?